The present invention relates to a shift device for operating a change transmission for four-wheel drive motor vehicles, which can also be driven selectively by only the front wheels or the rear wheels, and more particularly to a transmission having an auxiliary transmission combined with an ordinary main transmission and an auxiliary clutch device for disconnecting transmission of the power to a high gear ratio or a lower gear ratio, whereby the vehicle may be driven in a higher range four-wheel drive and a lower range four-wheel drive condition.
Such a transmission system is provided with a first shift-actuating device for the main transmission and a second shift-actuating device for the auxiliary transmission.
U.S. Pat. No. 4,170,273 discloses a shift lever for operating the auxiliary clutch device and the second shift-actuating device. Both devices are simply operated by shifting the shift lever along a straight line for selection of the two-wheel drive condition, a high range four-wheel drive condition and a lower range four-wheel drive condition. In order to position the shift lever at an intermediate position between the two-wheel drive position and the lower range four-wheel drive position, ball lock devices are provided. However, if the shift lever is operated with a powerful force from either the two-wheel drive position or the lower range four-wheel drive position, the shift lever is subject to pass beyond the intermediate position because of the weak action of the ball lock devices. Further, the operator may stop shifting the shift lever before the intermediate position, because the clicking action of the ball lock device is not felt, which results in an insufficient engagement in the transmission.